LEFT VENTRICULAR OUTFLOW OBSTRUCTION WITHOUT LEFT VENTRICULAR HYPERTROPHY

Kanji Iga MD, *Shuichi Takahashi MT, *Muneto Yamashita MT, Kenjiro Hori MD, Tadashi Matsumura MD, Hiromitsu Gen MD, and Kazuhisa Kijima, MD.

Abstract

<Background>

Cases of transient systolic anterior motion of the mitral valve and a systolic murmur in a structurally normal heart have been reported sporadically.

<Methods and Methods>

Among 7,558 adult patients in whom Doppler echocardiography was performed over a 2.5-year period at Tenri Hospital, we retrospectively studied thirteen consecutive patients who had both systolic anterior motion of the mitral valve without left ventricular hypertrophy and a peak velocity greater than 1.5 m/sec in the left ventricular outflow tract. Patients with concomitant significant aortic stenosis were excluded in this study.

< Results>

The mean age was 73 years and nine patients had a sigmoid septum. The left ventricle was rather small and hyperkinetic. A mid-systolic murmur that did not radiate to the carotid arteries was heard in all patients around the fourth left intercostal space. In four patients, the systolic murmur developed suddenly in association with unstable hemodynamics and tachycardia; two patients died soon thereafter, but in two other patient, repeat echocardiography when the heart murmur decreased in intensity showed that systolic anterior motion of the mitral valve had disappeared, and the peak left ventricular outflow tract velocity had decreased. Among the nine patients who had no significant acute illness, four were evaluated again ; systolic anterior motion of the mitral valve had disappeared and the left ventricular outflow tract velocity decreased in two patients.

<Conclusions>

We conclude that elderly individuals with a sigmoid septum are prone to develop a labile systolic murmur originating from the left ventricular outflow tract due to subtle hemodynamic changes.